Making real-time E. coli detection a reality

Every year, diseases caused by contaminated drinking water kills hundreds of thousands of people around the world. Detecting contamination early — before dangerous microorganisms have a chance to multiply — would save countless lives.

Right now, however, testing water samples means sending them to a lab. In remote communities, or even in big cities like Beijing where each building has its own water tank, that simply isn’t feasible. And even where it is feasible, it takes several days to get results.

Dr. Chang-qing Xu and Tianyi Guo are proposing a better alternative: an in-line analyzer that can test drinking water and produce results in less than an hour, without the need for lab facilities or technical expertise.

As a professor of engineering physics at McMaster University, Xu has spent years developing micro-flow cytometers and photonic sensors capable of detecting even low levels of E. coli, a bacteria that indicates water contamination. Now, Guo — the general manager of Hamilton’s Forsee Instruments — is incorporating those components into an automated, user-friendly and commercially viable device that could revolutionize water quality monitoring.

“There’s (at this moment) no similar product that is available on the market,” says Xu.

Tag, you’re it

The multi-stage process starts by passing a water sample through a ceramic membrane to help concentrate microorganisms, making them easier to detect. Next, the system tags E. coli with fluorescent antibodies that bind specifically to those bacteria. After that, the sample is pumped one cell at a time through the ultra-narrow channel of Xu’s micro-flow cytometer, which uses a laser to prompt the tagged cells emit light. The system then tallies up those glowing cells, providing an accurate estimate of bacterial numbers.

Currently, this type of approach is used in high-tech hospital diagnostic labs. Guo and Xu aim to make it affordable, simple and portable. “Our role is to reduce the flow cytometry to a microchip level,” Xu explains.

To do that, they face three main challenges. “Number one, you don’t want to miss any of the [E. coli] cells. Number two, you don’t want any miscounting,” says Xu. “Number three, you want the counting to be as fast as possible.”

They’ve made significant headway on the first challenge. Preliminary research shows that the micro-filtration system can successfully concentrate more than 90 per cent of E. coli cells, providing a highly accurate read on levels of water contamination.

In terms of miscounting, Xu is working to address this potential “cross-talk”: ensuring that the sensors can differentiate between E. coli and other particles. Although they’ve had good results in the lab using the antibodies, Xu is working with his biochemistry colleagues at McMaster to see if there are other approaches that could be even more effective.

But it’s the speed at which Forsee’s system can generate results that really promises to turn heads. Instead of waiting over a week for a lab report, users could have results in under an hour. In time, Xu hopes to get that number down to half an hour or even 10 minutes.

At Guo’s end, the challenge is to automate the system and create a tool that’s simple and easy to operate. “It’s very hard to make sure every component is working perfectly with each other,” he says. “If one little bubble goes inside the system, it will cause a problem.”

Powerhouse partners

The joint venture is part of the broader McMaster-Jiangsu International Technology Development and Translation Centre: a partnership with manufacturers and researchers in China to commercialize new water treatment and monitoring technologies.

With funding from the Advancing Water Technology (AWT) program, Forsee will collaborate with McMaster to help get the one-of-a-kind technology market-ready as soon as possible. The AWT program, which is supported by the Federal Economic Development Agency for Southern Ontario (FedDev Ontario), helps companies in Ontario leverage the province’s research facilities and academic expertise to develop water technologies with global potential. In addition to tapping into Xu’s research expertise, Forsee also benefits from access to industry-standard facilities needed for prototyping and testing. “For a small startup with a limited budget, that support makes a big difference,” says Guo.

A working prototype is nearing completion and Xu and Guo are looking ahead to field-testing the analyzer in several different communities across Ontario. If all goes well, Forsee could be shipping out sample devices to potential customers by the end of 2018.

“Without the AWT program, the process of this commercialization would be much slower,” Guo says.

High-impact results

Once it is commercially available, the technology promises to make a huge impact on public health around the world. Reliable, real-time access to water quality information — without the need for expensive labs or technical expertise — will help prevent outbreaks and save lives.

For Guo, that opportunity to provide a practical tool that addresses real-world problems is highly rewarding. “Doing my PhD program, I focused on research,” he says. “Now, I can make a real system, which can be used by everybody. I think that’s amazing.”